This invention relates generally to bearing cages for use with roller bearings and, more particularly, to bearing cages suitable for applications imposing high operating temperatures and severe inertia loads.
Bearing conditions existing within two- and four-cycle internal combustion engines are among the most severe. High loads, speeds, accelerations, and temperatures, particularly at crankpin and wristpin positions, make bearing selection critical. Needle roller and cage assemblies have found general acceptance as an optimum choice for meeting those extreme requirements.
Due to the proximity to combustion chambers and the piston's oscillating motion, the wristpin position has required a strong, hardened cage machined of steel and staked to retain the rollers. Commonly, such cages have end rims that are wider (axially) than would be considered normal for additional strength and to keep the roller length within connecting rod width. Minimum diameter rollers with minimum diametral clearance are used to reduce inertial loading.
In less demanding applications, bearing cages for roller bearings have been made of various polymers to minimize weight and reduce manufacturing cost. However, such polymer bearing cages have not been successful in wristpin positions and other severe applications because they lack sufficient strength and/or prevent adequate lubricant flow to the rollers.
The foregoing illustrates limitations known to exist in present cages for roller bearings. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one of more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.